docs(configuration): update webhooks.md — remove init reference, point to netclaw config (post-netclaw-dev/netclaw#1368)

[Aaronontheweb]

Context

Update src/content/docs/configuration/webhooks.md after netclaw-dev/netclaw#1368 ships.

Current

• Says "toggle during netclaw init"
• References init-09-webhooks.png

Inbound webhook configuration has moved entirely out of the init wizard and into netclaw config.

Should become

• "Enable via netclaw.json or netclaw config → Inbound Webhooks"
• Remove init-09-webhooks.png reference
• Optionally insert config-inbound-webhooks.png from sub-issue Update exposure/pairing docs and homepage hero copy #13 once available
• Link to cli/config.md for the full netclaw config reference

Screenshots or tapes needed

config-inbound-webhooks from sub-issue #13 (optional addition; not required if the existing JSON config docs are sufficient). Screenshot insertion gated on stable release.

Acceptance criteria

• No "toggle during netclaw init" language
• netclaw config → Inbound Webhooks path documented
• init-09-webhooks.png reference removed (no broken <img> refs)

Dependencies

• Can start copy changes now
• Sub-issue docs(cli): new page cli/config.md — netclaw config dashboard reference (post-netclaw-dev/netclaw#1368) #59 (cli/config.md) for cross-link
• Sub-issue Update exposure/pairing docs and homepage hero copy #13 for optional config-inbound-webhooks screenshot

Part of #55